Apparatus and method for generating constructively multi-patterned watermark, and apparatus and method for inserting and detecting the watermark using the same

Abstract

An apparatus and a method for generating a constructively multi-patterned watermark, an apparatus and a method for inserting and detecting the watermark using the same. The method includes dividing user's hidden data into plural partial data and outputs the plural partial data, performing a message-encoding of the plural partial data, modulating the plural message-encoded data into image signal format and outputting plural message signals, generating a synchronization signal for synchronizing the constructively multi-patterned watermark with a two-dimensional translation of an image, generating, plural sub-base patterns using the plurality of message signals modulated into the image signal format, and the synchronization signal, and generating a base watermark that is the constructively multi-patterned watermark, using the plural sub-base patterns. Therefore, the invention increases the payload of the watermark, withstands robustly the two-dimensional translation of an image and general geometric transform of the image through the constructive characteristics of the watermark.

What is claimed is: 
     
       1. An apparatus that generates a constructively multi-patterned watermark, comprising:
 a data divider that divides user's hidden data into a plurality of partial data and outputs the plurality of partial data; 
 an encoder that performs a message-encoding of the plurality of partial data; 
 a modulator that modulates the plurality of message-encoded partial data into image signal format to output a plurality of message signals; 
 a synchronization signal generator that generates a synchronization signal for synchronizing the constructively multi-patterned watermark with a two-dimensional translation of an image; 
 a sub-base pattern generator that generates a plurality of sub-base patterns using the plurality of message signals modulated into the image signal format, and the synchronization signal; and 
 a base watermark generator that generates a base watermark that is the constructively multi-patterned watermark, using the plurality of sub-base patterns. 
 
     
     
       2. The apparatus of  claim 1 , wherein the encoder performs the message-encoding of the plurality of partial data using an error correction code. 
     
     
       3. The apparatus of  claim 1 , wherein the data divider divides the user's hidden data into a N×N-number of partial data (N: natural number) and outputs the N×N number of partial data. 
     
     
       4. The apparatus of  claim 3 , wherein the data divider divides the user's hidden data into four of the partial data and outputs the four of the partial data. 
     
     
       5. The apparatus of  claim 4 , wherein the base watermark generator inserts each of 4 sub-base patterns into each corresponding area, in the form of a non-rotated, a 90 degree-rotated, a 180 degree-rotated, and a 270 degree-rotated pattern, respectively so as to generate the base watermark. 
     
     
       6. The apparatus of  claim 4 , wherein the base watermark generator inserts each of 4 sub-base patterns into each corresponding area, in the form of an original pattern, a vertically symmetrical pattern, a horizontally symmetrical pattern, and a vertically and horizontally symmetrical pattern, respectively so as to generate the base watermark. 
     
     
       7. An apparatus for inserting a constructively multi-patterned watermark, comprising:
 a raw data extractor that extracts raw data from an inputted original image; 
 a YUV space converter that converts color space of the extracted raw data into YUV color space and extracts a Y component from the YUV color space; 
 a constructively multi-patterned watermark generator that generates a plurality of sub-base patterns by dividing user's hidden data into a plurality of partial data, and generates, with the plurality of sub-base patterns, the constructively multi-patterned watermark that is a base watermark; and 
 a watermark inserter that determines a watermark insertion strength for insertion of the constructively multi-patterned watermark into the extracted Y component, and inserts the constructively multi-patterned watermark into the Y component by applying the determined watermark insertion strength to the extracted Y component. 
 
     
     
       8. The apparatus of  claim 7 , wherein the constructively multi-patterned watermark generator comprises:
 a data divider that divides the user's hidden data into the plurality of partial data and outputs the plurality of partial data; 
 an encoder that performs a message-encoding of the plurality of partial data; 
 a modulator that modulates the plurality of message-encoded partial data into image signal format to output a plurality of message signals; 
 a synchronization signal generator that generates a synchronization signal for synchronizing the constructively multi-patterned watermark with a two-dimensional translation of an image; 
 a sub-base pattern generator that generates a plurality of sub-base patterns using the plurality of message signals modulated into the image signal format and the synchronization signal; and 
 a base watermark generator that generates a base watermark that is the constructively multi-patterned watermark, using the plurality of sub-base patterns. 
 
     
     
       9. The apparatus of  claim 8 , wherein the data divider divides the user's hidden data into four of the partial data and outputs the four of the partial data. 
     
     
       10. The apparatus of  claim 9 , wherein the base watermark generator inserts each of 4 sub-base patterns into each corresponding area, in the form of a non-rotated, a 90 degree-rotated, a 180 degree-rotated, and a 270 degree-rotated pattern, respectively so as to generate the base watermark. 
     
     
       11. The apparatus of  claim 9 , wherein the base watermark generator inserts each of 4 sub-base patterns into each corresponding area in the form of an original pattern, a vertically symmetrical pattern, a horizontally symmetrical pattern, and a vertically and horizontally symmetrical pattern, respectively so as to generate the base watermark. 
     
     
       12. The apparatus of  claim 7 , wherein the watermark inserter inserts the constructively multi-patterned watermark into the Y component using the following formula:
     I′   n,m   =I   n,m +α r ·((1−MWMS n,m ) S   0 +MWMS n,m   S   1 )· w   n,m  
 
 where, I′ n,m  is watermarked contents, I n,m  is original contents, w n,m  is a watermark, α r  is a local watermark insertion strength, and S 0 , S 1  are fixed coefficients. 
 
     
     
       13. An apparatus for detecting a constructively multi-patterned watermark, comprising:
 a raw data extractor that extracts raw data from an image with the constructively multi-patterned watermark inserted; 
 a YUV space converter that converts color space of the extracted raw data into YUV color space, and extracts a Y component from the YUV color space; 
 a watermark detector that predicts a watermark detection strength from the extracted Y component, and detects the constructively multi-patterned watermark from the Y component applying the watermark detection strength; 
 a two-dimensional translation restorer that performs synchronization with respect to a two-dimensional translation of the image to restore the two-dimensional translation of the image; 
 a message code extractor that extracts a message code from a watermark signal where the two-dimensional translation is restored; and 
 a user's hidden data extractor that extracts user's hidden data from the extracted message code. 
 
     
     
       14. The apparatus of  claim 13 , further comprising:
 a geometric transform predictor that predicts a degree of geometric transform of the image; and 
 a geometric transform restorer that restores the geometric transform of the image by using the predicted degree of the geometric transform. 
 
     
     
       15. The apparatus of  claim 14 , wherein the geometric transform predictor measures auto correlation pattern of the detected constructively multi-patterned watermark, and extracts coordinates of pixels whose auto correlation values have a periodic pattern, in order to predict the degree of the geometric transform of the image. 
     
     
       16. The apparatus of  claim 15 , wherein the geometric transform restorer calculates an inverse transform parameter for the geometric transform of the image using the coordinates of pixels whose auto correlation values have a periodic pattern, and restores the geometric transform of the image using the inverse transform parameter. 
     
     
       17. The apparatus of  claim 16 , wherein the geometric transform restorer selects a group of four coordinates with a first highest peak value to a fourth highest peat value, respectively, among the coordinates whose auto correlation values have a periodic pattern, and then abandons restoring the geometric transform of the image if the  4 four coordinates meet any one of the following conditions:
 (1) each straight-line distance between any two of the  4 four coordinates is less than ½ of each straight-line distance between any two of the  4 four coordinates on an original image; 
 (2) each of the internal angles formed by connecting three coordinates is out of the range of 75 to 105 degrees; and 
 (3) a ratio of the lengths of two straight lines formed by connecting three coordinates is more than 1:2. 
 
     
     
       18. The apparatus of  claim 7 , wherein the watermark inserter performs a modeling for the extracted Y component using a probabilistic modeling to calculate a MWMS (Maximum Watermark Strength) using a ML (Maximum Likelihood) estimation or a MAP (Maximum A Posteriori) estimation for the modeling, divides image of the extracted Y component into partial images with a size of m×m pixels to calculate each local watermark insertion strength of the partial images according to a corresponding ratio of flat areas, edge areas and complex areas of each of the partial images, and inserts the constructively multi-patterned watermark into the Y component using the MWMS and the local watermark insertion strength. 
     
     
       19. The apparatus of  claim 8 , wherein the data divider divides the user's hidden data into a N×N number of the partial data (N: natural number) and outputs the N×N number of the partial data.